I just finished reading the Fionavar Tapestry by Guy Gavriel Kay. Borrowed the three books in one cover at the local library, in a Danish translation. I enjoyed the read, although the first book started slow. It shows that it was his first. The writing in the later books is much, much better.
Other great books I would recommend are the Hyperion series by Dan Simmons, and in similar vein the Riverworld series by Philip José Farmer. And the Foundation series by Isaac Asimov. And how could I not mention Ender's Game by Orson Scott Card.
I recently read the Earthsea series by Ursula K. Le Guin series. A bit boring at times, but otherwise good. They feel different than most fantasy/science fiction books I've read. Perhaps the gender of the author shows.
I have also read the series by David Eddings, they are not exactly great works of art. But they do their job, exciting.
I recently reread Midworld by Alan Dean Foster (it's called Grøn = Green in Danish, I didn't even know it was part of a series). I remembered it as a favourite, but was disappointed when I read it again. Too naive. I think I've had too much scientific training. It's like the Dragonlance books I used to read and really enjoy when I was young, at about the age of 15 they were simply unbearable.